This invention relates to solenoid-actuated valves of the type having a fluid pressure-operated diaphragm to control opening and closing of the valve, and has particular reference to a new and improved self-cleaning filter assembly for filtering control fluid used to operate the diaphragm.
Solenoid-actuated valves of the type having a fluid pressure-actuated diaphragm to control opening and closing of the valve have long been known in the art. Typically, such valves include a means for bleeding fluid pressure from the inlet side of the valve to a control chamber where the fluid bled from the inlet acts on the diaphragm to maintain the valve closed, a solenoid being provided to relieve the pressure in the control chamber to effect opening of the valve.
One problem connected with valves of this type is that the bleed passageways through which fluid passes to and from the control chamber are typically relatively small in diameter, and as a result, relatively easily clogged or blocked if dirt, grit, and other deleterious matter is not filtered from the control fluid prior to entering the control passageways. This is particularly true when the valve is used in connection with the operation of sprinklers for irrigation of lands supplied with water from wells, rivers, lakes, and the like.
Various attempts have heretofore been made at solving the problem of filtering the control fluid, typically by providing filters of various types at the inlet to the control fluid passageways or by providing filters in the control fluid passageways. Exemplary of such prior art devices are the filters used in the valves currently marketed by Rain Bird Sprinkler Mfg. Corp. of Glendora Cal. under its model designations E Series Electric Remote Control Valves, Model CP Contamination Proof Electric Valves, and EAV Series Electric Angle and Tee Pattern Remote Control Valves, shown respectively, on pages 50, 51 and 54 of the Rain Bird 1975-1976 Irrigation Equipment Catalogue.
While the filter assemblies used with valves of the above types have met with some success, there still remains a problem of the filter element itself becoming clogged or blocked, and which necessitates periodic disassembly of the valve or filter assembly to clean or replace the filter element. Thus, there exists a need for a filter assembly which is self-cleaning so as to prevent the filter element from becoming clogged or blocked during use, and which need not be periodically removed for cleaning or replacement by a clean filter.